Biocompatible and biodegradable polylactides/glycolides (PLA/PLGA) have received high attention over the last thirty years in the biomedical field as sutures, implants, colloidal drug delivery systems (Penning et al., 1993; Uhrich et al., 1999), and more recently also in tissue repairing and engineering (Liu and Ma, 2004; Stock and Mayer, 2001) and anti-cancer drug delivery (Mu and Feng, 2003; Jiang et al., 2005). Next to the medical field they are also widely used in the packaging area. As biodegradable “green polymers” they are preferable to the commodity polymers currently used (Drumright et al., 2000; Vink et al., 2003).
There is a crucial need of well-defined polylactide-based materials with advanced properties to fit all the requirements for the different applications. For example, PLA/PLGA homo- and co-polymers synthesized by the well-established ring opening polymerization (ROP) process (Dechy-Cabaret et al., 2004; Kricheldorf et al., 1995; Schwach et al., 1997; Degee et al., 1999; Ryner et al., 2001) have a glass transition temperature (Tg) limited to a range of only 40-60° C. (Jamshidi et al., 1988; Vert et al., 1984), independent of the polymer molecular weight and chemical composition. This combined with interesting mechanical properties makes them suitable in medical applications as biodegradable implants, bone fracture fixation devices, scaffolds for living cells.
These polylactides, however, have significant limitations for drug delivery purposes. For drug delivery purposes, polylactides need to be formulated with organic solvents and administered as solutions or in form of nano- and micro-particles, and polylactides cannot be injected on their own. Thus there is a significant need for a polylactide which may be used for drug delivery that does not require the use of an organic solvent or to form nano- and micro-particles.
WO2007/012979 discloses compositions and methods relating to polylactides which may be used for drug delivery which do not require the use of an organic solvent or to form nano- and micro-particles prior to injection. These polylactides may be used, for example, to administer a drug to a subject (e.g., a human patient) parenterally without the use of a solvent. More specifically, WO2007/012979 discloses compositions and methods of preparing a pharmaceutical preparation comprising a drug and an alkyl substituted polylactide; wherein the alkyl substituted polylactide is viscous; and wherein a solvent is not required for said admixing (the cited reference is herein incorporated by reference).
WO2012/014011 discloses compositions comprising polymers prepared by melt polycondensation of one or more substituted or unsubstituted C4-C32 2-hydroxyalkyl acids, method of preparing a pharmaceutical composition comprising thereof, and a method for delivering a bioactive agent to a subject, comprising administering to the subject an effective amount of the composition therein (the cited reference is herein incorporated by reference).
Fatty acid derivatives are members of class of organic carboxylic acids, which are contained in tissues or organs of human or other mammals, and exhibit a wide range of physiological activity. Some fatty acid derivatives found in nature generally have a prostanoic acid skeleton as shown in the formula (A):

On the other hand, some of synthetic prostaglandin (PG) analogues have modified skeletons. The primary PGs are classified into PGAs, PGBs, PGCs, PGDs, PGEs, PGFs, PGGs, PGHs, PGIs and PGJs according to the structure of the five-membered ring moiety, and further classified into the following three types by the number and position of the unsaturated bond at the carbon chain moiety:                Subscript 1: 13,14-unsaturated-15-OH        Subscript 2: 5,6- and 13,14-diunsaturated-15-OH        Subscript 3: 5,6-, 13,14-, and 17,18-triunsaturated-15-OH.        
Further, the PGFs are classified, according to the configuration of the hydroxyl group at the 9-position, into α type (the hydroxyl group is of an α-configuration) and β type (the hydroxyl group is of a β-configuration).
PGs are known to have various pharmacological and physiological activities, for example, vasodilatation, inducing of inflammation, platelet aggregation, stimulating uterine muscle, stimulating intestinal muscle, anti-ulcer effect and the like.
Prostones, having an oxo group at position 15 of prostanoic acid skeleton (15-keto type) and having a single bond between positions 13 and 14 and an oxo group at position 15 (13,14-dihydro-15-keto type), are fatty acid derivatives known as substances naturally produced by enzymatic actions during metabolism of the primary PGs and have some therapeutic effect. Prostones have been disclosed in U.S. Pat. Nos. 5,073,569, 5,534,547, 5,225,439, 5,166,174, 5,428,062, 5,380,709, 5,886,034, 6,265,440, 5,106,869, 5,221,763, 5,591,887, 5,770,759 and 5,739,161, the contents of these references are herein incorporated by reference.
Some fatty acid derivatives have been known as drugs used in the ophthalmic field, for example, for lowering intraocular pressure or treating glaucoma. For example, (+)-Isopropyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-[(3R)-3-hydroxy-5-phenylpentyl]cyclopentyl]-5-heptenoate (general name: latanoprost), Isopropyl(5Z)-7-((1R,2R,3R,5S)-3,5-dihydroxy-2-{(1E,3R)-3-hydroxy-4-[3-(trifluoromethyl)phenoxy]but-1-enyl}cyclopentyl)hept-5-enoate (general name: travoprost), (5Z)-7-{(1R,2R,3R,5S)-3,5-Dihydroxy-2-[(1E,3S)-3-hydroxy-5-phenylpent-1-en-1-yl]cyclopentyl}-N-ethylhept-5-enamide (general name: bimatoprost) and 1-Methylethyl(5Z)-7-{(1R,2R,3R,5S)-2-[(1E)-3,3-difluoro-4-phenoxy-1-butenyl]-3,5-dihydroxycyclopentyl}-5-heptenoate (general name: tafluprost) have been marketed as ophthalmic solution for the treatment of glaucoma and/or ocular hypertension under the name of Xalatan®, Travatan®, Lumigan® and Tapros®, respectively.
Some fatty acid derivatives have also been known as drugs used in systemic diseases for example, alprostadil (PGE1), beraprost (prostacyclin analog), limaprost (PGE1 derivative), misoprostol (PGE1 derivative), enprostil, dinoprost (PGF2α), gemeprost (PGE1 derivative) and epoprostenol (prostacyclin).
Further, prostones have also been known to be useful in the ophthalmic field, for example, for lowering intraocular pressure and treating glaucoma (see U.S. Pat. Nos. 5,001,153, 5,151,444, 5,166,178, 5,194,429 and 5,236,907), for treating cataract (see U.S. Pat. Nos. 5,212,324 and 5,686,487), for increasing the choroidal blood flow (see U.S. Pat. No. 5,221,690), for treating optic nerve disorder (see U.S. Pat. No. 5,773,471), the contents of these references are herein incorporated by reference. Ophthalmic solution comprising (+)-isopropyl (Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-(3-oxodecyl)cyclopentyl]hept-5-enoate (general name: isopropyl unoprostone, or unoprostone ispropyl) has been marketed under the name of Rescula® as a pharmaceutical product for the treatment of glaucoma and ocular hypertension. Also, isopropyl unoprostone is known as a BK channel modulator. (Biochimica et Biophysica Acta 1768 (2007) 1083-1092). Documents cited in this paragraph are herein incorporated by reference.